Nano-cellulose coatings to prevent damage in foodstuffs

ABSTRACT

Disclosed herein are embodiments of a composition for use in forming films or coatings that prevent damage in foodstuffs, including plants, fruits, and vegetables. The disclosed compositions comprise a cellulose nanomaterial and can further comprise a nanoscale mineral compound and one or more additional components. Also disclosed are films or coatings made using the disclosed compositions, as well as methods for making the disclosed compositions and methods for using the disclosed compositions.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 15/794,941, filedOct. 26, 2017, which is a division of U.S. application Ser. No.14/214,145, filed Mar. 14, 2014, now U.S. Pat. No. 9,826,750, whichclaims the benefit of U.S. Provisional Application No. 61/784,060, filedMar. 14, 2013; each of these prior applications is hereby incorporatedherein by reference in its entirety.

FIELD

This disclosure relates to the field of protective, edible coatings forfood or foodstuffs, such as plants, fruits, vegetables. It furtherrelates to compositions suitable as protective coatings and methods ofmaking and applying these compositions.

BACKGROUND

Finding acceptable coatings for foods, such as fresh fruits, vegetables,cheeses, bakery goods, raw and cooked eggs, fresh and processed meat andseafood products is a challenging task. The desired coating would beedible and once applied would act as a barrier to moisture, gases and/orUV light, and undesirable microorganisms. However, several othercriteria must also be met. The coating must be completely harmless toconsumers, transparent, or nearly so, in the visible region so theproduct is visible to the consumer, and impart no significant odor ortaste to the foods. In addition, edible coatings that offer promise aspackaging materials due to one or more unique functional propertiesoften suffer from reduced water resistance (highly water soluble).Satisfying all these criteria simultaneously and satisfactorily haspresented a serious challenge to researchers and as yet no suitablesolution has been found.

Anthocyanins provide the majority of red, purple, and blue pigmentationof fruits, and their greater consumption has been suggested to mitigatethe risk of chronic disease in humans. Unfortunately, these pigments arehighly labile and vulnerable to degradation during thermal processing.Further complicating matters is their water-solubility that promotestheir leaching into aqueous media. Thus, innovative technologies areneeded to overcome long-standing technical barriers experienced by thefood industry to retain these health-promoting pigments during cropproduction, harvesting, handling and processing.

Fresh produce (fruits and vegetables) and plants in general commonlylose water to their surroundings during production, harvesting, handlingand storage. This water loss can cause damage, dieback, and death toplants in general, as well as changes in the appearance, texture andquality of the produce, which most consumers find unappealing. Thisresults in a decreased marketability, and limits acceptable shelf-lifeand storage times.

Exposure to high levels of UV light can damage developing and maturingproduce creating visibly damaged and discolored tissues, destroyingnative healthful phytochemical compounds, stimulating production ofundesirable and harmful compounds like ethylene gas, and providing afoothold for spoilage organisms to grow. Such produce suffers a loss ofperceived quality, reduced health benefits and generally deemedunsuitable for the fresh market. Further, the phenomenon can potentiallyruin a grower economically, as the conditions leading to its occurrenceare shared by the entire crop.

Previously frozen foods typically exude liquid during thawing, resultingin a phenomenon called “drip loss.” This can be off-putting toconsumers, and can change the overall composition of the thawed product,making it behave differently from fresh during preparation/cooking. Driploss also can cause economic losses to the processors.

SUMMARY

This invention utilizes a material, nanocellulose (which has notpreviously been used as an edible coating), alone or in combination withnano calcium carbonate for the protection from moisture loss and UVdamage of plant tissues and organs in general and fresh fruits andvegetables both pre- and post-harvest and also as a barrier coating forother fresh and processed foods for preventing leaching of functionalfood substances, such as anthocyanins and other water soluble compounds,as well as loss and/or gain of moisture and gases (e.g. H₂O, O₂, andCO₂) during food processing and storage.

Disclosed herein are embodiments of a composition, comprising acellulose nanomaterial in an amount selected from 0.188%, 0.375%, 0.75%,or 1%, and 0.1% of a nanoscale mineral compound. Embodiments of thecomposition are edible. The composition may further comprise a phenoliccompound, a crosslinking agent, an acid, a metal ion, or combinationsthereof. In other embodiments, the composition may further comprise afilm-forming material, a plasticizer, an antimicrobial agent, anantioxidant agent, or combinations thereof.

The cellulose nanomaterial may be selected from cellulose nanofibrils,cellulose nanocrystals, or a combination thereof. In some embodiments, aportion of the cellulose nanomaterial may comprise cellulosemicrofibrils, cellulose microcrystals, or a combination thereof. Thedisclosed nanoscale mineral compound can be nano-calcium carbonate.Suitable film-forming materials include chitosan, a protein, fruit orvegetable puree, or combinations thereof.

In some embodiments, the composition may comprise a cellulosenanomaterial in an amount selected from 0.188%, 0.375%, 0.75%, or 1%;0.1% of a nanoscale mineral compound; and a crosslinking agent, whereinthe composition is formulated for preventing or mitigating pre- and/orpost-harvest damage in a plant, fruit, vegetable, or part thereof. Thecomposition may be formulated for preventing or mitigating leaching ofanthocyanins, nutrients, pigments, or combinations thereof from theplant, fruit, vegetable, or part thereof. The composition also may beformulated for preventing or mitigating weight loss and UV damage of theplant, fruit, vegetable, or part thereof.

Also disclosed herein is a plant, fruit, vegetable, or part thereof,comprising a film formed from the composition embodiments disclosedherein. The plant, fruit, vegetable or part thereof can be substantiallycoated with the composition. In some embodiments, the fruit is ablueberry, a cherry, or an apple. The plant, fruit, vegetable, or partthereof that is coated with the composition exhibits reduced anthocyaninleaching, moisture loss, gas exchange, or nutrients loss compared to aplant, fruit, vegetable, or part thereof that is not coated with thecomposition. In some embodiments, the plant, fruit, vegetable, or partthereof coated with the composition exhibits reduced weight loss afterthawing compared to a plant, fruit, vegetable, or part thereof that isnot coated with the composition.

Methods for treating a plant, fruit, vegetable, or part thereof also aredisclosed. In some embodiments, the method comprises substantiallycoating the plant, fruit, vegetable, or part thereof with a compositionembodiment disclosed herein before or after the plant, fruit, vegetable,or part thereof is harvested. The plant, fruit, vegetable, or partthereof can be substantially coated with the composition by spraying,dipping, enrobing, or combinations thereof. In some embodiments, themethod further comprises processing the plant, fruit, vegetable, or partthereof to prevent or mitigate leaching of anthocyanins, nutrients,pigments, or combinations thereof in the plant, fruit, vegetable, orpart thereof. Processing the plant, fruit, vegetable, or part thereofcan comprise thermal processing at a temperature of at least 80° C. Insome embodiments, the method can further comprise washing the plant,fruit, vegetable, or part thereof after processing to substantiallyremove the composition. Such method embodiments can further compriseperforming an additional thermal processing step after the plant, fruit,vegetable, or part thereof is washed. In some embodiments, processingthe plant, fruit, vegetable, or part thereof can comprise freezing theplant, fruit, vegetable, or part thereof substantially coated with thecomposition.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIGS. 1A-1E are photographic images of blueberries after performing twothermal processing steps, film removal, and one day of storage inpacking water in ambient conditions. FIG. 1A is an image of uncoatedblueberries; FIG. 1B is an image of blueberries that were coated with acomposition comprising 1% cellulose nanofibrils prior to the firstthermal processing step; FIG. 1C is an image of blueberries coated witha composition comprising 1% cellulose nanofibrils and 0.01% nano-calciumcarbonate (NCC) prior to the first thermal processing step; FIG. 1D isan image of blueberries coated with a composition comprising 1%cellulose nanofibrils, the coating being applied by spray coating priorto the first thermal processing step; and FIG. 1E is an image ofblueberries coated with a composition comprising 1% cellulosenanofibrils and 0.01% NCC, the coating being applied by spray coatingprior to the first thermal processing step.

FIGS. 2A-2C are photographic images of blueberries coated with differentcomposition embodiments disclosed herein after different thermalprocesses. FIG. 2A is an image of blueberries after thermal processingat 80° C. for 20 minutes, with the blueberries being coated with CNFprior to thermal processing; FIG. 2B is an image of the blueberriesillustrated in FIG. 2A after the coating was removed and the blueberrieswere subjected to another thermal process at 65° C. for 15 minutes; andFIG. 2C is an image of the blueberries of FIGS. 2A and 2B after beingstored in water for one day in ambient conditions.

FIG. 3 is a graph of monomeric anthocyanin concentration (mg/L) andpigment absorbance (measured at 525 nm) leached from coated and uncoatedblueberries after processing (80° C. for 20 minutes) and cooling (20minutes).

FIG. 4 is a graph of monomeric anthocyanin concentration (mg/L) andpigment absorbance (measured at 525 nm) leached from processedblueberries (65° C. for 15 minutes) after one day of storage in ambientconditions.

FIGS. 5A and 5B are photographic images illustrating the appearance ofuncoated and coated apple rings after freezing processes. FIG. 5Aillustrates non-coated apples and FIG. 5B is an image of apple ringscoated with a composition comprising 1% cellulose nanofibrils and 0.01%NCC.

FIG. 6 is a graph of tensile strength (MPa, N/mm²) and elongation atbreak (%) illustrating results obtained from analyzing films ofcarboxymethyl cellulose and films made using various embodiments of thedisclosed composition. The different letters provided on the bars inFIG. 6 represent significant difference (P<0.05) of tensile strength.

FIGS. 7A-7E are microscope images (magnified by 10×) illustrating themicrostructures of various types of films under UV light. FIG. 7Aillustrates a film comprising carboxymethyl cellulose; FIG. 7B is animage of a film comprising 0.188% cellulose nanofibrils; FIG. 7C is animage of a film comprising 0.188% cellulose nanofibrils and 0.01% NCC;FIG. 7D is an image of a film comprising 0.375% cellulose nanofibrils;and FIG. 7E is an image of a film comprising 0.375% cellulosenanofibrils and 0.01% NCC.

FIG. 8 is a bar graph of fluence (mJ/cm²) measurements obtained uponirradiation of the surface of cylindrical vessels containing 0.6 M KI,0.1 M KIO₃, and 0.01 M Na₂B₄O₇.10H₂O (n=2; mean values). Results areprovided for vessels without films (control), vessels covered with acarboxymethyl cellulose film, and vessels having films formed usingembodiments of the disclosed composition. Different letters on the barrepresent significant difference (P<0.05) of UV fluence.

FIG. 9 is a bar graph of transmittance (T, %) of visible (measured at620 nm) or UV (measured at 280 nm) light transmissions passing throughvarious types of films disclosed herein (n=3, mean values).

FIGS. 10A-10E are photographic images of treated apples after UVexposure and storage. FIG. 10A is an image of an uncoated apple; FIG.10B is an image of an apple coated with a composition comprising 1%cellulose nanofibrils; FIG. 10C is an image of an apple coated with acomposition comprising 1% cellulose nanofibrils and 0.01% NCC; FIG. 10Dis an image of an apple coated with a composition comprising 1%cellulose nanofibrils, applied by spray coating; and FIG. 10E is animage of an apple coated with a composition comprising 1% cellulosenanofibrils and 0.01% NCC, applied by spray coating.

DETAILED DESCRIPTION

The nano-cellulose coatings described herein mitigate the leaching ofpigments and nutrients in fresh and processed fruits and vegetables. Inmethods described herein we have prepared aqueous suspension slurries offibrous or crystalline nano-cellulose coatings that form a durable,inert, water-resistant coating over the foodstuff. The coatings formedfrom the suspensions/slurries with the addition of other ingredients,including, but not limited to, plasticizers, minerals, chitosan,protein, antimicrobial and antioxidant agents, and other functionalingredients when applied will protect foodstuffs from water loss,protect from sunburn damage and protect from the loss of physicalintegrity, all of which are responsible for significant qualitydeterioration, microbial spoilage and monetary losses to the foodindustry. The nano-cellulose coating is aqueous in nature, and thus doesnot require waxes, oils or other solvents to apply, and it is based onedible cellulose. The coating solution is formulated with ingredientsthat are commonly found in food (e.g. cellulose, calcium carbonate,water, glycerin, etc.) and it has the potential to allay consumerconcerns over food safety.

Described herein are materials comprising cellulose nanofibrils (CNF)and nano calcium carbonate (NCC). Cellulose nanomaterial is cellulosicmaterial comprising linear chains of one hundred to over ten thousandP-0-glucopyranose units linked by glucosidic bonds at their C1 and C4positions, with any external dimension in the nanoscale or havinginternal structure or surface structure in the nanoscale. Cellulosenanomaterials are composed in whole or in part of cellulose nanofibril(CNF) or cellulose nanocrystal (CNC), which can be present in a mixturewith cellulose microcrystal (CMC) or cellulose microfibril (CMF).

In the methods reported here, the nanofibril (CNF) structure andcompound properties have been adjusted to provide a type of cellulosenanofiber that contains both crystalline regions and amorphous regions,with dimensions of 3 to several hundred nm in width, aspect ratiogreater than 50 (for CNF) or 10 (for CNC), reminiscent of elementaryfibrils in plant cell walls. There are many methods used in thepreparation of CNF, e.g. fibrillation with or without chemicalpretreatment in the mechanical refining of cellulose derived from woodfiber or non-wood plant fiber, and may or may not contain residualhemicelluloses. In some embodiments, the method of preparing CNFs caninclude fibrillation methods with or without chemical pretreatment inthe mechanical refining of cellulose such as, but not limited to woodfiber or non-wood plant fiber, and may or may not contain residualhemicelluloses. The primary attribute of the disclosed CNFs and CNCsuseful for this invention is that they form an acceptably clear,water-resistant coating.

Based on the foundation of nanocellulose films, the utilization ofnanoscale mineral fillers for UV protection also is disclosed. Thus,described herein are materials comprising nanoparticles, nanodots ornanopowder calcium carbonate (NCC) that are cubic and high surface areaparticles. NCC has a particle size of 60-100 nm when examined byScanning Electron Microscopy (SEM). Existing applications for NCC hasfocused on use as an agricultural additive, in drug delivery by loadingthem with hydrophilic protein-based drugs and for their potentialimaging, biomedical and bioscience properties and for use in coatings,plastics, nanowire, and in alloy and catalyst applications.

Also intended is the incorporation of additional agents for thestabilization and retention of anthocyanins in fruits, vegetables, andother foods during processing to provide for enhanced shelf life,storage, and consumer appeal. Examples of the agents useful in thedisclosed compositions include: phenolics (such as, but not limited totannic acid and other phenolic acids); acids (such as, but not limitedto formic acid and citric acid); crosslinking agents (such as, but notlimited to sodium trimetaphosphate (food grade crosslinking agent) andpyruvic acid); and metal ions (such as, but not limited to food-gradestannous (Sn) chloride). When applied to the surface of fruits,vegetables and other foods, cellulosic coating solutions form a strongexternal barrier after drying. The nanocellulose-based coating mitigatesthe loss of color appearance and physical integrity associated with theleaching of pigments, nutrients, and water-soluble compounds intosurrounding water or other aqueous solution and when subjected to theheat, pressure, and other effects of the foodstuff preparation andprocessing. This barrier prevents or greatly lessens the leaching ofbioactive pigments/nutrients during thermal or other types ofprocessing. NCC is useful as an anti-transpirant, to prevent water lossin produce before and after harvest.

The compositions disclosed herein can be used to preventpigments/nutrients leaching from other fruits and/or vegetables otherthan those expressly disclosed herein. The compositions also can be usedto for reducing water loss/gain for foodstuffs (baked goods, such ascookies; candies; and other confections) during storage. Alsocontemplated herein are compositions that are useful to reduce gas(e.g., O₂ and CO₂) exchanges of various foods with air in theenvironment. The present disclosure also concerns uses of the disclosedcompositions in applications, such as modifying the physical propertiesof biodegradable products such as boards, films and packages, including:increased resistance to degradation; improved barrier properties; andimproved strength. The compositions also can be used to make protectivecoatings for durable materials to present damage during transit andhandling.

In another embodiment described herein, films and other flexiblepackages made from aqueous solutions/slurries of fibrous or crystallinenano-cellulose are extremely water resistant and strong. Films and otherflexible packages comprising combinations of nano-cellulose and otherexisting film forming materials (including, but not limited to:chitosan, protein and fruit/veg puree) provide improved water resistanceand barrier properties while retaining the unique functionality of thenon cellulose materials. The nano-cellulose coatings protect objectsfrom water loss due to transpiration and/or freeze-thaw related driploss and allows for improved water resistance and barrier propertieswhile retaining the unique functionality of the non cellulose materials.

EXAMPLES Example 1

In one embodiment, cellulose nanofibrils (CNF) comprising bothcrystalline regions and amorphous regions are described, with dimensionsof 3 to several hundred nm in width, aspect ratio greater than 50,reminiscent of elementary fibrils in plant cell walls.

The method of preparation of CNF are formed by fibrillation methods withor without chemical pretreatment in the mechanical refining of cellulosesuch as, but not limited to wood fiber or non-wood plant fiber, and mayor may not contain residual hemicelluloses.

Nanoparticles, nanodots or nanopowder calcium carbonate (NCC) are cubicand high surface area particles. Nanoform calcium carbonate has aparticle size of 60-100 nm when examined by Scanning Electron Microscopy(SEM). Existing applications for NCC has focused on use in drug deliveryby loading them with hydrophilic protein-based drugs and for theirpotential imaging, biomedical and bioscience properties and for use incoatings, plastics, nanowire, and in alloy and catalyst applications

Table 1 provides the formulations of CNF and NCC coating andfilm-forming solutions used in certain embodiments disclosed herein. Thegiven amount of CNF and/or NCC was dissolved in deionized water and thenhomogenized using a homogenizer for reaching complete dissolution of CNFand CNN at ambient conditions.

TABLE 1 Formulation of CNF and NCC coating and film-forming solutions.Code Formulation† NF316 0.188% CNF NF316C 0.188% CNF with 0.01% NCC NF380.375% CNF NF38C 0.375% CNF with 0.01% NCC NF34 0.750% CNF NF34C 0.750%CNF with 0.01% NCC NF 1 1% CNF NF 1C 1% CNF with 0.01% NCC NF 1S 1% CNFby spray coating NF 1CS 1% CNF with 0.01% NCC by spray coating CMCCarboxymethyl cellulose †All formulations were prepared by dispersingthe components in deionized water.

Example 2

Coating of blueberries with aqueous slurries of 1-2% cellulosenanofibrils as described in Table 1, with and without the addition ofnano calcium carbonate, virtually eliminated the leakage of anthocyaninpigments (compared with a control) from blueberries during thermalprocessing analogous to that seen in the industry. Results are discussedbelow.

Example 3

In another embodiment described herein, the prevention ofpigment/nutrient leaching from blueberry fruits is disclosed. Duringthermal processing, bioactive pigments and nutrients (e.g. anthocyanins)can be leached from the fruit into the surrounding aqueous media,typically water or low sugar solution, causing a change in appearance(loss of natural fruit pigments) and possible nutritional losses.

Blueberries were coated with different CNF and NCC solutions asdescribed in Table 1 by either dipping fruit in coating solution(dipping blueberries in the coating solution for 1 minute and then driedat room conditions) or spray-coating (coating solution was sprayed onthe surface of blueberries under 30 psi pressure and then dried at roomconditions). Non-coated and coated blueberries were packed in glass jars(50 ml) filled up with distilled water, put inside a water bath withcontrolled temperature, and then subjected to three processconditions: 1) heating at 80° C. for 20 minutes; 2) heat at 65° C. for15 minutes; and 3) a sequence of conditions (1) and (2). To determinewhether CNF coatings could prevent this phenomenon, colors andanthocyanin content in the packing water after thermal processing of theblueberries were tested. The color of packing water was measured by UVspectrophotometer at 525 nm (Shimadzu, Japan). For measuring monomericanthocyanin of the packing water, a method by Giusti and Wrolstad (2001)was used to measure the monomeric anthocyanin content of the packingwater. See, Giusti, Monica M., and Ronald E. Wrolstad, “Characterizationand Measurement of Anthocyanins by Uv-Visible Spectroscopy,” In CurrentProtocols in Food Analytical Chemistry, edited by Ronald E. Wrolstad,F1.2.1-F1.2.13. New Jersey: John Wiley & Sons, Inc., 2001, which isincorporated herein by reference in its entirety. After the firstthermal process (80° C. for 20 minutes), coating was removed from thesurface of fruits by washing using tap water, uncoated fruit were thensubjected to the second thermal treatment (65° C. for 15 minutes) toexamine whether the protective effect would remain.

FIGS. 1A-1E illustrate that the leaching of pigments/anthocyanin waseliminated or greatly reduced by the CNF/NCC coatings, compared withuncoated blueberries (control). Even after the coating was removed afterthe first thermal treatment, pigment leaching was negligible after the2nd stage of thermal treatment, as illustrated in FIGS. 2A-2C. Further,the coating formulations containing NCC showed lower levels of leachingcompared to those without as shown in FIGS. 3 and 4. Method of coatingapplication also had a marked effect, with spray-coating applicationsperforming markedly better than analogous dipped coating applications,showing significantly lower contents of pigments and anthocyanin inpacking solutions.

Example 4

In another embodiment described herein are formulations of compoundsuseful as food coatings and in preparation of frozen foods to preventdrip loss and in maintain integrity during thawing. Foodstuffsexperience significant water loss during the freezing and thawingprocess due to syneresis (i.e., water loss after thawing) andevaporation.

Apples were peeled, cored and cut into slices of uniform thickness. Theresultant slices were then dipped in CNF coating solutions or leftuncoated prior to freezing in a forced air freezer (−20° C. for 24hours). Afterwards, the samples were removed from the freezer andallowed to thaw at ambient temperature (18-23° C. for about 6 hours.Measurements were taken of both the change in mass during freezing(condensation) and the total amount of liquid exuded from the thawingapples (syneresis and evaporation).

Overall, the total weight loss (%) after thawing of coated apple sliceswas lower than that of uncoated apples shown in Table 2. Additionally,it was found that the condensation which formed on the thawing applesdue to ambient humidity in the thawing room was higher on the uncoatedslices (FIG. 5A) compared to the coated ones (FIG. 5B). As can be seenby comparing FIGS. 5A and 5B, uncoated apples appeared more desiccateddue to higher levels of moisture loss compared with coated samples.

TABLE 2 Comparison of condensation (%) and weight loss (%) betweennon-coated and CNF coated fresh-cut apples Parameters TreatmentsCondensation (%) Weight loss (%) Non-coated apples 8.87 ± 1.19 21.09 ±3.54 NF1 6.48 ± 0.51 17.33 ± 2.38 NF1C0.01 6.28 ± 0.53 17.94 ± 2.54

Example 5

In another embodiment described herein are the methods to prepare CNFflexible, water-resistant films useful as an edible food packaging wrapthat may be applied for packaging wide varieties of food products. Themajority of flexible packaging materials in the food industry arepetroleum-derived polymers. Their lack of sustainability and concernsover toxic residues result in decreased appeal to consumers. Instead,alternate natural materials (e.g. cellulose and chitosan) lackwater-resistance.

Solutions comprising 0.188 and 0.375% CNF were prepared, casted inTeflon-coated glass plate, and dried at room temperature for 72-96 hours(Chen and Zhao, 2012). See, Chen, J. and Zhao, Y., “Effect of molecularweight, acid, and plasticizer on the physicochemical and antibacterialproperties of beta-chitosan based films,” J. Food Sci. 77(5), E127-136,which is incorporated herein by reference in its entirety. A 1% CMCsolution was also prepared to make films as a comparison with our CNFfilms. Prepared films were conditioned for 48 hours in a 25° C. and 50%relative humidity (RH) environmental chamber. Conditioned film sampleswere tested for moisture content, water solubility, and water-vaportransmission rate (WVTR), as well as tensile strength and elongation.Moisture content of the films was determined by the percentage weightloss of film samples after drying in a forced-air oven at 100° C. for 24hours. Water solubility was determined by the percentage weight loss offilms samples after suspension in water for 24 hours and dried at 40° C.for 24 hours, whereas CMC film was only tested for 2 hours due to itshydrophilicity. WVTR was measured by the cup method at 25° C. and100/50% RH gradient, following ASTM Standard Method E96-87 (ASTM, 2000).Tensile strength (TS) and percent elongation at the break (EL) of thefilms were determined according to ASTM 0882 (ASTM, 2001) and analyzedusing a texture analyzer (TA.XT2i, Texture Technologies Corp., USA) byfollowing the same procedures as Park and Zhao (2004). See, Park, Su-il,and Yanyun Zhao, “Incorporation of a High Concentration of Mineral orVitamin into Chitosan-Based Films,” Journal of Agricultural and FoodChemistry 52, no. 7 (2004): 1933-1939, which is incorporated herein byreference in its entirety.

Overall, the physicochemical properties of CNF films were significantlybetter than CMC films, indicating the former had a higher level ofwater-resistance as shown in Table 3. Tensile strength and elongationprovided interesting results, with the CMC film showing the greatestelongation and the second highest tensile strength, being surpassedslightly by films of formulation NF38, as shown in FIG. 6. Thesedifferences are likely related to the differences in the concentrationand resultant film thickness, as the CMC solution had more than twicethe concentration, and resulted in a much thicker film (0.083 mm) thanNF38 (0.019 mm) as shown in Table 3. Microstructure tests showed thatadding NCC into CNF films significantly improved the homogeneity of thefilms as can be seen by comparing FIGS. 7B and 7D with FIGS. 7C and 7E.All films have a very homogeneous structure, and NCC is very evenlydistributed in the film matrix of the samples illustrated in FIGS. 7Cand 7E (visible as pink dots in the colored version of these figures).

TABLE 3 Moisture contents (MC, %), water solubility (Ws, %), and watervapor transmission rate (WVTR, g mm/d m²) for various types of films.Measured parameters Types of film MC Film Thickness Ws WVTR CMC* 15.865^(a)  0.083 62.067 ^(a)  131.840 ^(a)  NF316** 4.206 ^(c) 0.014 0.123^(b) 13.186 ^(b) NF316C*** 4.266 ^(c) 0.014 0.240 ^(b) 22.818 ^(b) NF38⁺6.016 ^(b) 0.019 0.176 ^(b) 24.948 ^(b) NF38C⁺⁺ 5.905 ^(b) 0.030 0.216^(b) 25.391 ^(b) *1% carboxymethyl cellulose **0.188% cellulosenanofibrils ***0.188% cellulose nanofibrils added with 0.01% CaCO₃⁺0.375% cellulose nanofibrils ⁺⁺0.375% cellulose nanofibrils added with0.01% CaCO₃ Means preceded by the same letter in the same column withinsame experiment were not significantly different (P > 0.05).

Example 6

In another embodiment described herein are the methods providing UVsunburn protection within CNF/NCC coatings and films before and afterharvest. Exposure to high levels of UV light can damage maturingproduce, resulting in visibly discolored spots, destroying phytochemicalcompounds, and providing a foothold for spoilage organisms to grow.

UV protective films with CMC and CNF solutions were prepared followingthe same procedures described above and used to cover the top ofcylindrical acrylic vessels containing 10 ml buffered liquid dosimetrysolution (0.6 M KI, 0.1 M KIO₃, and 0.01 M Na₂B₄O₇.10H₂O). Fluencemeasurements (mJ/cm²) were obtained by subjecting the vessels to ultraviolet light for a fixed time and then measuring the change in theabsorbance of the solution at 352 nm, as shown in FIG. 8. Transmittanceof visible and UV light was also determined using spectrophotometry at620 nm and 280 nm. Additionally, coating solutions were applied to wholeapples (Malus domestica, var. golden delicious) using either spraying ordipping methods. After the coatings had dried, the samples, plusuncoated samples were placed in under a 10 W UV source for 1.5 hours toinduce UV damage. Samples were stored at ambient temperature for 12 daysand periodically assayed for color and weight loss (%), and photographedto record changes in appearance.

All films showed a significant reduction in the fluence of UV light,with CNF films outperforming the CMC film as shown in FIG. 8. Thetransmittance (%) of both visible and UV light were quite high for CMCfilms (81.4 and 55.7%, respectively), compared to the transmittancethrough the CNF-based films, which ranged from 14.4 to 29.5% for visiblelight and 7.9-27.3% for UV as shown in FIG. 9. The addition of NCC to agiven formulation provided for marked decreases in transmittance (%) ofvisible and UV light, reducing them by as much as a third or more.Treated apples had no significant difference in color before and aftercoating, but after UV exposure and storage significant increases wereobserved in the color intensity (chroma) between the uncoated “control”apples and the apples coated with all but one formulation (NF1C)described in Table 4. See also FIGS. 10A-10E, which illustrate theappearance of uncoated (FIG. 10A) and coated apples (FIGS. 10B-10E)after being exposed to UV light for 1.5 hours after 12 days. Significantincreases were observed in the color intensity (Chroma) for the coatedapples. In all but one case (NF1C), no change in weight loss (%) wasfound. It must be noted that this is likely due to the relatively shortstorage time and the great degree of variation within sample groups.

TABLE 4 Comparison of ΔL, ΔE, Δhue, Δchroma, and weight loss (%) betweennon-coated and coated whole apples for 12 days† ΔL Δhue Δchroma ΔEWeight loss (%) Control −3.067 0.249 10.399    14.83 5.67 NF1* −3.133−0.635 6.519 (*)    11.58 (*) 5.16 NF1C**    −1.767 (*) 1.293 6.372 (*)11.37    4.35 (*) NF1S⁺ −2.867 −3.630 5.410 (*) 12.22 4.92 NF1CS⁺⁺−3.100 0.568 6.700 (*) 11.68 5.11 †Mean values (n = 6), values followedby an asterix (*) denote significant difference from the control value,as determined by t-testing (α = 0.05) *1% cellulose nanofibrils **1%cellulose nanofibrils added with 0.01% CaCO₃ ⁺1% cellulose nanofibrilsby spray coating ⁺⁺1% cellulose nanofibrils added with 0.01% CaCO₃ byspray coating

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim as our invention all that comes within the scope and spirit ofthese claims.

We claim:
 1. A plant, fruit, vegetable, or part thereof, coated with afilm formed from a composition comprising 0.188 wt % to 2 wt % of acellulose nanomaterial comprising cellulose nanofibrils, cellulosenanocrystals, or a combination thereof and further comprising cellulosemicrofibrils, cellulose microcrystals, or a combination thereof; whereinthe film formed from the composition prevents or mitigates pre- and/orpost-harvest damage in the plant, fruit, vegetable, or part thereof. 2.The plant, fruit, vegetable, or part thereof of claim 1, wherein thecomposition further comprises a phenolic compound, a crosslinking agent,an acid, a metal ion, or combinations thereof.
 3. The plant, fruit,vegetable, or part thereof of claim 1, wherein the composition furthercomprises a film-forming material, a plasticizer, an antimicrobialagent, an antioxidant agent, or combinations thereof.
 4. The plant,fruit, vegetable, or part thereof of claim 1, wherein the compositionfurther comprises chitosan, a protein, fruit or vegetable puree, orcombinations thereof.
 5. The plant, fruit, vegetable, or part thereof ofclaim 1, wherein the composition is edible.
 6. The plant, fruit,vegetable, or part thereof of claim 1, wherein the composition furthercomprises a crosslinking agent.
 7. The plant, fruit, vegetable, or partthereof of claim 1, wherein the film prevents or mitigates leaching ofanthocyanins, pigments, nutrients, water soluble compounds orcombinations thereof from the plant, fruit, vegetable, or part thereof.8. The plant, fruit, vegetable, or part thereof of claim 1, wherein thefilm prevents or mitigates weight loss and/or UV damage of the plant,fruit, vegetable, or part thereof.
 9. The plant, fruit, vegetable orpart thereof of claim 1, wherein the fruit is a blueberry, a cherry, oran apple.
 10. The plant, fruit, vegetable, or part thereof of claim 1,wherein the plant, fruit, vegetable, or part thereof exhibits reducedanthocyanin leaching, nutrient leaching, moisture loss, or gas exchangecompared to a plant, fruit, vegetable, or part thereof that is notcoated with the composition.
 11. The plant, fruit, or vegetable of claim1, wherein plant, fruit, vegetable, or part thereof exhibits reducedweight loss after thawing compared to a plant, fruit, vegetable, or partthereof that is not coated with the composition.
 12. A method oftreating a plant, fruit, vegetable, or part thereof, comprising coatingthe plant, fruit, vegetable, or part thereof, before or after the plant,fruit, vegetable, or part thereof is harvested, with a compositioncomprising 0.188 wt % to 2 wt % of a cellulose nanomaterial comprisingcellulose nanofibrils, cellulose nanocrystals, or a combination thereofand further comprising cellulose microfibrils, cellulose microcrystals,or a combination thereof to provide a film that prevents or mitigatespre- and/or post-harvest damage in the plant, fruit, vegetable, or partthereof.
 13. The method of claim 12, wherein the plant, fruit,vegetable, or part thereof is coated with the composition by spraying,dipping, enrobing, or combinations thereof.
 14. The method of claim 12,wherein the method further comprises processing the plant, fruit,vegetable, or part thereof to prevent or mitigate leaching ofanthocyanins, nutrients, pigments, or combinations thereof in the plant,fruit, vegetable, or part thereof.
 15. The method of claim 14, whereinprocessing the plant, fruit, vegetable, or part thereof comprisesthermal processing at a temperature of at least 80° C.
 16. The method ofclaim 15, wherein the method further comprises washing the plant, fruit,vegetable, or part thereof after processing to remove the film.
 17. Themethod of claim 16, wherein the method further comprises performing anadditional thermal processing step after the plant, fruit, vegetable, orpart thereof is washed.
 18. The method of claim 12, wherein processingthe plant, fruit, vegetable, or part thereof comprises freezing theplant, fruit, vegetable, or part thereof coated with the composition.19. A method for processing a coated plant, fruit, vegetable, or partthereof, comprising thermally processing the coated plant, fruit,vegetable, or part thereof at a temperature of at least 80° C., whichcoated plant, fruit, vegetable, or part thereof is coated with a filmformed by a composition comprising 0.188 wt % to 2 wt % of a cellulosenanomaterial comprising cellulose nanofibrils, cellulose nanocrystals,or a combination thereof and further comprising cellulose microfibrils,cellulose microcrystals, or a combination thereof.